1. Technical Field
The present invention relates to a polishing apparatus and a polishing method.
2. Related Art
Polishing of a polished surface of a wafer is carried out in, for example, a CMP (Chemical Mechanical Polish) step of a semiconductor manufacturing process using CMP polishing apparatus.
Polishing apparatus illustrated in FIG. 11 are disclosed in Japanese Laid-Open Patent Publication No. H9-254018. The polishing apparatus illustrated in FIG. 11 is equipped with a polishing table 201, a support unit 202 for supporting the subject of polishing, a dressing tool (corresponding to a conditioning disc) 203, a nozzle 204 for spraying water in order to clean or wet the support unit 202, and a nozzle 205 for spraying water in order to clean or wet the dressing tool 203. The nozzles 204, 205 are located to the side of the polishing table 201 at a position lower than the upper surface of the polishing table 201. During washing or wetting of the support unit 202 and the dressing tool 203, as shown in FIG. 11, the support unit 202 and the dressing tool 203 are moved to positions to the side of the polishing table 201 lower than the upper surface of the polishing table 201.
Polishing apparatus illustrated in FIG. 12 are disclosed in Japanese Laid-Open Patent Publication No. 2000-263417. This polishing apparatus includes a polishing table 301, a polishing pad 302 located above the polishing table 301, a slurry supply tube 303, a support unit 305 for supporting a wafer 304, a dresser (corresponding to a conditioning disc) 307 having the brush 306 at a lower surface, and a washing mechanism 308 for washing the brush 306. At this polishing apparatus, as illustrated in FIG. 12, the brush 306 projects from the polishing table 301 and is washed by the washing mechanism 308 from below both during and after polishing.
Polishing apparatus illustrated in FIG. 13 are also disclosed Japanese Laid-Open Patent Publication No. 2000-263417. This polishing apparatus is equipped with a polishing table, a polishing pad 302 located above the polishing table, a slurry supply tube 303, a support unit 305 supporting the wafer 304, a dresser 307 having a brush 306 at a lower surface, and a nozzle 309 for spraying water under high pressure in order to wash the brush 306. As shown in FIG. 13, this polishing apparatus washes the brush 306 by spraying water under high pressure onto the brush 306 from the nozzle 309 located to the side of the brush 306 that performs conditioning on the polishing pad 302.
However, with the polishing apparatus of Japanese Laid-Open patent publication No. H9-254018 (FIG. 11), it is necessary for the dressing tool 203 to be moved to a position lower than the upper surface of the polishing table 201 to the side of the polishing table 201 every time the conditioning disc is washed or wetted. This means that substantial amount of time is required to move the dressing tool 203 for washing or wetting.
In Japanese Laid-Open Patent Publication No. 2000-263417, washing is carried out mainly while carrying out conditioning with the brush 306 in contact with the polishing pad 302 with the structures for either of FIG. 12 or 13. This means that when fixed matter within the slurry becomes affixed to the brush 306, the fixed matter is swept out to the side of the subject of polishing (wafer etc.) by the brush 306 during washing and causes the subject of polishing to become scratched.
It is therefore extremely difficult to achieve a situation where both the time required to move the conditioning disc in order that the conditioning disc is washed or wetted is made short and the occurrence of scratches on a subject of polishing such as a wafer is sufficiently suppressed.